Process of manufacturing lead pigments.



Nq. 720,6'70.- V PATENTED FEB; 17, 1903;

- A. 0. J. GHARLIER,

PROCESS-0F MANUFACTURING LEAD PIGMENTS. AYPLIOATION FILED APR. 4,- I902.

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UNITED STATES PATENT Canton.

ANDREW CHARLES J O SEPH CHARLIER, OF GLASGOW, SCOTLAND.

PROCESS OF MANUFACTURING LEAD PIGMENTS'.

SPECIFICATION forming part of Letters Patent No. 720,670, dated February17, 1903. Application filed April 4, 1902. SerialNo.101,369. onspecimens.)

To aZZ whom it may concern:

Be it known that 1, ANDREW CHARLES Jo- SEPH CHARLIER, a subject of theKing of Great Britain, and a resident of Glasgow, Scotland, haveinvented certain new and useful Improvements in the Manufacture ofMetallic Compounds, of which the following is a full, clear, and exactspecification.

This invention, which relates to the manufacture of lead pigments andlead or other nietallic compounds, has for its object to lessen the costof and reduce the time heretofore necessary for the manufacture of suchcompounds.

The manufacture of lead compounds is carried on under pressure of thenecessary gas, and the present invention is designed to improve theconditions under which the chemical reaction takes place and to indicateapparatus suitable for use in such manufacture.

The apparatus in which the chemical reaction is carried out isillustrated under two modifications by Figures 1 and 2 of theaccompanying drawings.

In carrying out the present invention in respect to the manufactureofcarbonate of lead I take a quantity of oxid of lead or litharge andplace it, together with a quantity of water slightly acidified withacetic acid, in a vessel or vat a, such as shown at Fig. 1, providedwith an inlet (1, normally closed bya cover 6, into which vessel carbondioxid from a cylinder or reservoir 0 is admitted, by way of a reducingor other valve f, to the vessel or vat at a pressure which experimentshave shown to be advantageous and important in so far that it hastensthe chemical reaction, these experiments having demonstrated that whenthe gasused is at a pressure of about two hundred pounds to the squareinch the chemical reaction is most efiective.

The vessel or vat a, by which full advantage is taken of the action ofthe carbondioxid gas upon the acidified water, and consequently upon theoxid of lead, and which constitutes an inseparable part of theinvention, is preferably mounted upon an axle or trunnions b, situatedeither transversely of the axis of the cylinder, as shown at Fig. 1, orupon said axis, as shown at Fig. 2, so that the said cylinder may berotated or oscillated by hand or power transversely of its axis, as atFig. 1, or about its axis, as at Fig. 2, the

object being, by means-of an action calculated to break up or spray theliquid within the cylinder'a, to cause a thorough carbonation of theliquid, and consequently a quicker chemical reaction. In twenty minutesa considerable portion of the oxid of lead or litharge will be found tobe converted into white lead, and the whole process, which formerlyrequired three months for its completion, can be completed within,a fewhours, the result being the obtaining of white lead entirely free fromoxid of lead or litharge with a pure color and equal in covering powerand opacity to the best white lead. The acid mixed with the water in thecylinder a is not employed to dissolve the litharge, but merely acts asa carrier, and by means of the pressure of carbon-dioxid gas it combineswith the litharge and forms white lead. Means, such as are shown at Fig.1, may when a continuous supply of gas is desired be provided by formingone of the trunnions b with a central passage communicating directly orindirectly with the interior of the cylinder or vessel a and connectedto the gas-reservoir, whereby a continuous pressure of gas may beobtained and the necessity for breaking thejoint between the vessel aand the gas-reservoir c in order to recharge said vessel or beingrendered unnecessary, the

trunnion admitting of the oscillation or rotationof the cylinder undersuch connection, or the continuous supply can be obtained; as shown atFig. 2, by carrying the gas-reservoir c alongside of the vat a, so as tobe rotated ANDREW CHARLES JOSEPH CHARLIER.

Witnesses:

ROBERT BROWN, JAMES MCCLURE, Jr.

